首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   41274篇
  免费   3054篇
  国内免费   276篇
耳鼻咽喉   411篇
儿科学   1209篇
妇产科学   747篇
基础医学   5959篇
口腔科学   701篇
临床医学   4358篇
内科学   8843篇
皮肤病学   801篇
神经病学   4113篇
特种医学   1563篇
外国民族医学   11篇
外科学   5690篇
综合类   512篇
一般理论   32篇
预防医学   3247篇
眼科学   824篇
药学   2861篇
中国医学   104篇
肿瘤学   2618篇
  2023年   326篇
  2022年   546篇
  2021年   1053篇
  2020年   716篇
  2019年   957篇
  2018年   1130篇
  2017年   909篇
  2016年   1028篇
  2015年   1092篇
  2014年   1490篇
  2013年   1843篇
  2012年   2887篇
  2011年   2993篇
  2010年   1694篇
  2009年   1425篇
  2008年   2292篇
  2007年   2550篇
  2006年   2372篇
  2005年   2174篇
  2004年   2035篇
  2003年   1744篇
  2002年   1611篇
  2001年   770篇
  2000年   726篇
  1999年   663篇
  1998年   379篇
  1997年   284篇
  1996年   291篇
  1995年   259篇
  1994年   210篇
  1993年   169篇
  1992年   390篇
  1991年   358篇
  1990年   343篇
  1989年   297篇
  1988年   296篇
  1987年   330篇
  1986年   334篇
  1985年   298篇
  1984年   248篇
  1983年   198篇
  1982年   140篇
  1981年   138篇
  1980年   134篇
  1979年   252篇
  1978年   179篇
  1977年   151篇
  1976年   139篇
  1974年   140篇
  1973年   148篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The rubric complementary medicine covers a variety of approaches that may seem alike only in their being outside conventional care and training. We have asked experienced practitioners to present their own pieces of this jigsaw, realising that these clinical fragments, when seen together, create excitement but also confusion. Of course, this forum is not intended to be a comprehensive review of relevant complementary treatments, and often the individual apporaches to clinical problems will appear totally unrelated, while their apparent effectiveness stretches the biomedical model and conventional research methodology beyond their capacity. With this in mind, we intend that forthcoming articles and reviews will expand on the therapies themselves, and discuss the evidence supporting them.  相似文献   
102.
We developed a technique that allows the routine integration of PET in stereotactic neurosurgery, including radiosurgery. We report our clinical experience with the combined use of metabolic (i.e., PET) and anatomic (i.e., MRI and CT) images for the radiosurgical treatment of brain tumors. We propose a classification describing the relative role of the information provided by PET in this multimodality image-guided approach. METHODS: Between December 1999 and March 2003, 57 patients had stereotactic PET as part of their image acquisition for the planning of gamma knife radiosurgery. Together with stereotactic MRI and CT, stereotactic PET images were acquired on the same day using either (18)F-FDG or (11)C-methionine. PET images were imported in the planning software for the radiosurgery dosimetry, and the target volume was defined using the combined information of PET and MRI or CT. To analyze the specific contribution of the PET findings, we propose a classification that reflects the strategy used to define the target volume. RESULTS: The patients were offered radiosurgery with PET guidance when their tumor was ill-defined and we anticipated some limitation of target definition on MRI alone. This represents 10% of the radiosurgery procedures performed in our center during the same period of time. There were 40 primary brain lesions, 7 metastases, and 10 pituitary adenomas. Abnormal PET uptake was found in 62 of 72 targets (86%), and this information altered significantly the MRI-defined tumor in 43 targets (69%). CONCLUSION: The integration of PET in radiosurgery provides additional information that opens new perspectives for the optimization of the treatment of brain tumors.  相似文献   
103.

Background  

Late stage cancer malignancies may result in severe skeletal muscle wasting, fatigue and reduced quality of life. Resistance training may attenuate these derangements in cancer patients, but how this hypertrophic response relates to normal muscle adaptations in healthy subjects is unknown. Here, we determined the effect of resistance training on muscle mass and myosin heavy chain (MHC) isoform composition in plantaris muscles from tumor-bearing (TB) rats.  相似文献   
104.
Breathing can lead to organ motions up to several centimeters. For radiotherapy of lung, these motions are generally taken into account by adding a specific margin around the target. Thus, treated volumes are often too large to allow for the high-dose values requested for local control. To manage respiratory motion, deep-inspiration breath-hold technique (DIBH) and gated radiotherapy are starting being used clinically. DIBH consists in asking the patient to perform breath-hold during the treatment and the image acquisition, DIBH level being measured by a spirometer. Gated radiotherapy consists in treating the patient at a certain phase of the free breathing. Linac is synchronized with the motion of a marker located on the patient chest. Planning images are obtained by a four-dimensional CT (4D-CT) using the same marker. We have assessed the value of these two methods. For lung treatment, compared to a standard treatment, toxicity reduction was mainly due to the lung total volume increase. It is therefore more significant for breath-hold approach. It is also due to the reduction of safety margins, which is similar for both methods. These two techniques, which have specific advantages and drawbacks, are used routinely at Curie Institute for a large proportion of lung patients, but also for some breast, liver or even Hodgkin disease treatments.  相似文献   
105.
Risk analysis in resection of squamous cell carcinoma of the esophagus   总被引:10,自引:2,他引:8  
A study of risk factors that affect morbidity and mortality in 523 patients with squamous cell cancer of the esophagus who had one-stage resection was undertaken. The 30-day and hospital mortality rates were 5.0% and 15.5%, respectively. Pulmonary complications, malignant cachexia, and surgical complications accounted for 42%, 25%, and 21% of hospital deaths, respectively. Major pulmonary complications occurred in 23% of patients. Multivariate analysis identified six factors that predicted major pulmonary complications: age, mid-arm circumference, percent of predicted FEV1, abnormal chest radiograph, amount of blood loss, and palliative resection. Three risk groups of pulmonary complications were identified: low, median, and high risk group with complications in 3%, 17%, and 43% of patients, respectively. Significantly, patients with curative resection had a lower hospital mortality rate (9%) than those with palliative resection (20%), p=0.001. Patients with stage I, IIa, or IIb disease had a lower hospital mortality rate (9%) than those with stage III or IV disease (18%), p=0.026. Multivariate analysis identified six factors that predicted hospital death: age, mid-arm circumference, history of smoking, incentive spirometry, number of stairs climbed, and amount of blood loss. Three risk groups of hospital death were identified: low, median, and high risk groups with death in 7%, 30%, and 38%, respectively. Anastomotic leakage rate was 4%. Technical faults were identified in 53% of patients with leakage. Together with other surgical complications, a presumed or apparent technical error was noted in 63% of patients. The identification of high-risk patients and prevention of technical faults can help improve surgical outcome.
Resumen Se emprendió un estudio sobre los factores de riesgo que afectaron la mortalidad en 523 pacientes con carcinoma escamocelular del esófago sometidos a resección en una etapa en nuestra institución.Las tasas de mortalidad a 30 días y de mortalidad hospitalaria fueron 5% y 15%. Las complicaciones pulmonares, caquexia maligna y quirúrgica representaron 42%, 25% y 21% de las muertes hospitalarias, respectivamente. Complicaciones pulmonares mayores fueron registradas en 23% de los pacientes.El análisis multivariado identificó seis factores que predicen complicaciones pulmonares mayores: edad, circunferencia del brazo, porcentaje del FEV1 predecible, radiografía de tórax anormal, pérdida de sangre durante la operación y resección de tipo paliativo. Se identificaron tres grupos de riesgo de desarrollar complicaciones pulmonares: bajo, medio y alto, con tasas de 3%, 17% y 43% de los pacientes, respectivamente. Los pacientes que recibieron resección curative exhibieron una significativamente menor tasa de mortalidad hospitalaria (9%) en comparación con los que recibieron resección paliativa (20%), p=0.001. Los pacientes con enfermedad en estados I, IIa, IIb exhibieron menor mortalidad hospitalaria (9%) en comparación con los estados III o IV (18%), p=0.026. El análisis multivariado identificó seis factores que predicen mortalidad hospitalaria: edad, circunferencia del brazo, historia de tabaquismo, espirometría de incentivo, número de escalones que puede ascender y pérdida de sangre durante la operación. Se identificaron tres grupos de riesgo de mortalidad hospitalaria: bajo, medio y alto, con tasas de 7%, 30% y 38% respectivamente.La tasa de fuga anastomótica fue 4% y se identificaron defectos técnicos en 53% de los pacientes. Junto con otras complicaciones quirúrgicas, se observó un error técnico presumible o aparente en 63% de los pacientes.La identificación de los pacientes de alto riesgo y la prevención de los errores técnicos pueden ayudar a mejorar el pronóstico.

Résumé Dans cette étude, on a étudié les facteurs de risque influençant la morbidité et la mortalité chez 523 patients ayant un cancer épidermoïde de l'oesophage et ayant eu une résection en un seul temps. La mortalité à 30 jours et la mortalité hospitalière ont été respectivement de 5% et de 15.5%. Les complications pulmonaires, la cachexie maligne et les complications chirurgicales ont été responsable respectivement de 42%, 25% et 21% des décès hospitaliers. Une analyse multifactorielle a permis d'identifier six facteurs prédictifs des complications pulmonaires: l'âge, la circonférence brachiale, la prévision du volume expiratoire forcé en une seconde, les anomalies de la radiographie thoracique, la quantité de sang perdu, et le caractère palliatif de la résection. Trois groupes, dont le risque de complications pulmonaires a été classé faible, moyen et élevé, ont été identifiés. Le taux de complications dans ces groupes ont été respectivement de 3%, 17% et 43%. Les patients ayant eu une résection à visée curative avaient une mortalité hospitalière significativement plus basse (9%) comparée à celle des patients ayant eu une résection à visée palliative (20%) (p=0.001). Les patients ayant des maladies de stades I, IIa, IIb avaient une mortalité plus basse (9%) que ceux qui avaient des stades III ou IV (18%), (p=0.026). L'analyse multifactorielle a permis d'identifier six facteurs prédictifs de la mortalité hospitalière: l'âge, la circonférence brachial, des antécédents de consommation excessive du tabac, la spirométrie, le nombre d'escaliers que le patient peut monter, et la quantité de sang perdu. Trois groupes de patients, dont le risque de mortalité hospitalière a été classé faible, moyen, et élevé, ont eu des décès dans respectivement 7%, 30% et 38% des cas. Le taux de fistule a été de 4%. Une faute technique a été identifiée chez 53% des patients ayant eu une fistule. Une faute technique apparente ou présumée a été identifie chez 63% des patients ayant eu soit une fistule soit une complication chirurgicale. L'identification des patients à haut risque et la prévention des fautes techniques peuvent contribuer à améliorer le pronostic après chirurgie.
  相似文献   
106.
In a 3-year period, 63 consecutive patients with advanced perforated (n=53) and gangrenous (n=10) appendicitis were allocated to undergo either immediate wound closure or delayed primary wound closure after emergency appendectomy. The incidence of wound infection between delayed primary wound closure and immediate wound closure was similar (24.0% and 21.1%, respectively). The duration for complete healing of infected wounds was slightly shorter in the group undergoing delayed primary wound closure (mean +/- SD, 24.3 +/- 9.2 days) than in the group undergoing immediate wound closure (mean +/- SD, 32.6 +/- 16.5 days), but the difference was not significant. However, healing of noninfected wounds was significantly prolonged in the group undergoing delayed primary wound closure (mean +/- SD, 19.3 +/- 10.1 days) compared with the group undergoing immediate wound closure (mean +/- SD, 7.0 +/- 0 days). The latter had been shown to associate with more nonseptic wound complications and therefore required longer rehabilitation. Our study showed that delayed primary closure did not offer additional advantage over immediate closure in the treatment of wounds associated with advanced appendicitis in children.  相似文献   
107.
The aim of this study was to carry out quantitative analyses of eye movements during the cover test on a group ( n = 57) of asymptomatic emmetropes. Eye movements were recorded during an automated cover test while subjects fixated a distance (3.4 m) and near (0.4 m) target. There was a significant difference between the amplitude of phoria measured after 2 s of occlusion compared to 10 s ( P < 0.01). The mean phoria after 10 s of occlusion was 0.1° (eso) for distance fixation and 1.6° (exo) for near fixation. The distribution was approximately normal for both distance and near fixation but the standard deviation was greater for near (2.0°) than distance fixation (1.4°). The pattern of eye movements during the recovery phase was more complex than is often assumed, in many cases consisting of a variety of saccadic and vergence movements involving both the covered and 'fixing' eye. The latency of the first recovery movement was significantly shorter for exophoric than esophoric deviations ( P < 0.01) and the latency of some recovery movements were very short (< 150 ms).  相似文献   
108.
BACKGROUND: Influenza transmission in households is a subject of renewed interest, as the vaccination of children is currently under debate and antiviral treatments have been approved for prophylactic use. AIMS: To quantify the risk factors of influenza transmission in households. DESIGN OF STUDY: A prospective study conducted during the 1999 to 2000 winter season in France. SETTING: Nine hundred and forty-six households where a member, the index patient, had visited their general practitioner (GP) because of an influenza-like illness were enrolled in the study. Five hundred and ten of the index patients tested positive for influenza A (subtype H3N2). A standardised daily questionnaire allowed for identification of secondary cases of influenza among their household contacts, who were followed-up for 15 days. Of the 395 (77%) households that completed the questionnaire, we selected 279 where no additional cases had occurred on the day of the index patient's visit to the GP. METHODS: Secondary cases of influenza were those household contacts who had developed clinical influenza within 5 days of the disease onset in the index patient. Hazard ratios for individual clinical and demographic characteristics of the contact and their index patient were derived from a Cox regression model. RESULTS: Overall in the 279 households, 131 (24.1%) secondary cases occurred among the 543 household contacts. There was an increased risk of influenza transmission in preschool contacts (hazard ratio [HR] = 1.85, 95% confidence interval [CI] = 1.09 to 3.26) as compared with school-age and adult contacts. There was also an increased risk in contacts exposed to preschool index patients (HR = 1.93, 95% CI = 1.09 to 3.42) and school-age index patients (HR = 1.68, 95% CI = 1.07 to 2.65), compared with those exposed to adult index cases. No other factor was associated with transmission of the disease. CONCLUSION: Our results support the major role of children in the dissemination of influenza in households. Vaccination of children or prophylaxis with neuraminidase inhibitors would prevent, respectively, 32-38% and 21-41% of secondary cases caused by exposure to a sick child in the household.  相似文献   
109.
Objective   To profile the expression of all known members of the matrix metalloproteinase ( MMP ), a disintegrin and metalloproteinase with thrombospondin motifs ( ADAMTS ), and tissue inhibitor of metalloproteinases ( TIMP s) gene families in normal cartilage and that from patients with osteoarthritis (OA).
Methods   Human cartilage was obtained from femoral heads at joint replacement for either osteoarthritis or following fracture to the neck of femur. Total RNA was purified and expression of genes assayed using quantitative real-time PCR.
Results   Several members of the above gene families were regulated in OA. Genes increasing in expression in OA were: at P  < 0.001, MMP-13 , MMP-28 , ADAMTS-16 ; at P  < 0.01, MMP-9 , MMP-16 , ADAMTS-2 , ADAMTS-14 and at P  < 0.05, MMP-2 , TIMP-3 , ADAMTS-12 . Genes decreasing in expression in OA were: at P  < 0.001, MMP-1 , MMP-3 , ADAMTS-1 ; at P  < 0.01, MMP-10 , TIMP-1 , ADAMTS-9 and at P  < 0.05, TIMP-4 , ADAMTS-5 , ADAMTS-15 . Correlation analysis revealed that groups of genes across the gene families are co-expressed in cartilage.
Conclusion   This is the first comprehensive expression profile of all known MMP , ADAMTS and TIMP genes in cartilage. Patterns of expression provide a foundation on which to understand mechanisms of gene regulation in OA and potentially for refining the specificity of anti-proteolytic therapies.  相似文献   
110.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号